Staff Engineer

About us: 

pay.com.au is one of Australia’s fastest‑growing technology scale-ups, trusted by businesses. As we continue to scale in Australia and launch into the US under PayRewards.com, our mission is to simplify and supercharge the way they pay everyday expenses. Since 2019, we’ve been transforming business payments by enabling companies—from sole traders to large enterprises. 

Our unified platform lets users link their bank accounts and any major credit card, improving cash flow while unlocking powerful rewards on every transaction.  

Recognised as a rapidly scaling Australian success story—with coverage in outlets like the Australian Financial Review noting our growth with a $600++ million valuation we’re reshaping how businesses think about payments, loyalty and financial efficiency.  

At pay.com.au, you’ll join a fast-growing team shaping the future of B2B payments. Our Melbourne office is a hub of creativity, collaboration, and seriously great coffee—an environment where ideas move quickly and impact is felt every day. If you want to be part of a company with momentum, this is the place to be.    

Why join us? 

• Be part of an exciting Tech Scale-up, with teams across Australia and the USA.   
• Enjoy flexible working arrangements and a great work-life balance. 
• Awarded 2025 People’s Choice Award winner at the Finder Innovation Awards, Finalist for FinTech Organisation of the Year at the 2025 FinTech Australia Finnies, Number 1 on the Smart50 list 2024, Top 3 Deloitte Tech Fast 50 & Victoria State Champion! 
• Grow your career in a culture that values creativity, innovation, and collaboration with access to learning budgets to accelerate your career. 
• Our new Pay HQ in Windsor brings together great coffee, collaborative spaces, and the kind of energy that makes doing your best work easy. 

Staff Engineer. 

We are standing up a new tribe around the two moments that decide whether a business stays with pay: the first five minutes, and every reward they claim after that. 

Two squads sit inside it. Activation owns signup, ABN and identity verification, authentication and the path to a first successful payment — the surface where conversion is won or lost. Rewards own the points earnt and redemption, the ledger behind them, and the integrations into our airline and hotel transfer partners, where a business turns everyday spend into flights, hotel nights or a paid-off invoice. 

The Staff Engineer is the senior technical voice across both squads — two systems that fail in opposite ways. The job is deciding what gets built now, what gets deferred and what never gets built and staying close enough to the code to defend those calls. With two squads shipping in parallel, the standards set here compound fast, in either direction. 

An individual contributor role, influence comes from technical judgement, working code and the decisions this person enables in others, not reporting lines. 

Responsibilities  

• Own the technical direction for identity, authentication and authorisation across the customer journey: session management, MFA and passkeys, multi-user and multi-business access, and the permissions model that governs what directors, bookkeepers and advisors can each do 
• Own the architecture of the rewards ledger and redemption paths, with a bias toward auditability, idempotency and correctness under partial failure 
• Lead the design of transfer partner and third-party integrations so that partner outages degrade gracefully rather than propagate 
• Raise the experimentation bar across both squads: sound metric definition, sensible sample sizing, guardrail metrics, clean event instrumentation in Amplitude, and honest read-outs including the negative ones 
• Set the observability standard for Growth surfaces: meaningful SLOs, useful dashboards and alerts in Datadog, and traces that shorten time to diagnosis rather than adding noise 
• Write and review ADRs, and make architectural trade-offs explicit including cost, delivery speed and the option value of deferring a decision 
• Improve the paved road so the squads move faster by default: developer experience, deployment safety, test strategy and continuous deployment enablement 
• Lift the engineers around them through pairing, design review and well-pitched feedback, and stay close enough to the codebase to be credible 
• Partner with Product, Growth, Marketing and Data as a peer in shaping what gets built, not just how 

About You 

• Substantial experience designing, building and operating production systems at scale. Our stack is TypeScript, React, Postgres and AWS 
• Deep, practical experience with authentication and authorisation: OAuth 2.0 and OIDC, session and token lifecycle, MFA and passkeys, and designing permissions models that survive contact with real organisational structures 
• Fluent in the fundamentals of experimentation, including what makes a test trustworthy and when the result does not support the conclusion being drawn from it 
• A pragmatic approach to system design: builds for the scale actually in front of them with a clear path to the next order of magnitude, and can articulate why a simpler design is the right call 
• Strong observability practice, ideally with Datadog. Treats instrumentation as part of the definition of done rather than something added after an incident 
• A track record of uplifting engineers. Reviews to teach, not to gate. Comfortable being disagreed with and changing their mind in public 
• Clear written communication, and the judgement to pitch the same decision differently for an engineer, a PM and an executive 

We know not everyone will meet every requirement, and that’s okay. If you’re excited about the role and believe you can make an impact, we’re keen to hear from you.  

A few more things… 

Successful candidates joining the team will need to complete a National Police Record Check. 

Candidates who require adjustments at any stage of the recruitment process are encouraged to let us know. We’re happy to support you.  

We’re committed to an inclusive and diverse recruitment process where everyone feels respected and supported. We welcome applicants from all backgrounds, identities and abilities and ensure fair, equitable consideration at every stage.